When image data from a computer is printed or copied by an image forming apparatus (or MFP: Multi Functional Peripheral) in an office environment, the printing is often executed only once. Even when the image to be printed is saved in the internal memory or hard disk of the apparatus, the data is erased immediately.
If a user uses a function (so-called box function) of intentionally saving, in a memory, raster data which has undergone raster image processing (RIP) to print an image later, printing can be done after changing some limited settings such as the number of copies and the post processing function.
In the print-on-demand (POD) market, a job which has been printed previously is invoked and printed again in many cases (to be referred to as “reprint” hereinafter). Hence, it is essential for efficient operation to save even printed data to prepare for reprint.
Raster data after RIP is excellent in print performance and can be printed immediately. However, changeable job properties are limited to, e.g., the number of copies and the post processing function. On the other hand, in data before RIP (e.g., PDL data described in a page description language (PDL)), any job property can be changed, though RIP is time-consuming. Both data before and after RIP can also be saved in the memory. However, when a number of large job data are saved, a hard disk with a large capacity or a large number of hard disks are necessary, resulting in an increase in cost for data saving.
In Japanese Patent Application Laid-Open No. 2003-006035, an original image file is copied and saved in a predetermined area of a storage device before image file correction processing. After correction processing, the original image file is replaced with the image file after correction processing.